Embedded Duck

This HTML document has a duck image embedded as base64 data URI at the bottom. The bottom image is invisible and used for loading only. Once the image is loaded, it fills the placeholder image. This way, the rest of the page is rendered first.
To simulate a slow connection, you can press
Ctrl+Shift+M
in Firefox and set throttling in the top bar. For Chrome, you need to open the Development Console first by pressing
Ctrl+Shift+I
.
Picture of a duck swimming in blue water. Image Credits , under CC BY-SA 3.0 license
Here comes some text that should be rendered before the image loaded.